Heidar, Rimewind Master + Intruder Alarm + Dual Nature + Ashnod's Altar + Phyrexian Walker

Heidar, Rimewind Master

Intruder Alarm

Dual Nature

Ashnod's Altar

Phyrexian Walker

How it works

1. Cast Phyrexian Walker by paying 0.
2. When Phyrexian Walker enters the battlefield, Intruder Alarm and Dual Nature's first ability triggers.
3. Resolve the Intruder Alarm trigger, untapping all creatures.
4. Resolve the Dual Nature trigger, creating a token copy of Phyrexian Walker.
5. Activate Ashnod's Altar by sacrificing the Phyrexian Walker token, adding CC.
6. Activate Heidar by paying 2 and tapping it, returning Phyrexian Walker to your hand from the battlefield.
7. Dual Nature's second ability triggers, exiling nothing.
8. Repeat.

This intricate loop spins into motion the moment you cast Phyrexian Walker for free, triggering both Intruder Alarm and Dual Nature to flood the battlefield with a fresh token copy of the Walker. Each time a creature enters, Intruder Alarm untaps your entire team—allowing you to continually untap Heidar, Rimewind Master (assuming you control four or more snow permanents to satisfy its activation requirement). You can then sacrifice the newly minted Walker token to Ashnod's Altar to generate colorless mana, and use a portion of that energy to fund Heidar, Rimewind Master's ability, bouncing the original Phyrexian Walker back to your hand so the whole cycle can begin anew.